This invention relates to printing machines and more particularly to screen printing machines which include ultraviolet radiation means for curing of printed subject matter. In a typical application, the printing machine may be employed for labeling plastic containers, and the ultraviolet radiation means is utilized for curing of the subject matter of the label.
U.S. Pat. No. 4,411,191 provides a disclosure discussing printing machines of the general type involved. Such machines include conveyor means having spaced-apart article carriers for accommodating plastic containers or other articles to be printed in the machine. A plurality of work stations may be located along the conveyor including a flame treatment station, a printing station, and a curing station where polymer-based printing materials or the like are employed. In the case of printing operations utilizing solvent based printing materials, a drying station may be associated with the machine or conveyor means may be employed for delivering the containers to some other location for drying.
In the operation of a printing machine of the type described in the aforementioned patent, the drive means for the conveyor provide for intermittent advance of the article carriers to the respective stations. At these stations, the articles are adapted to be picked off the carriers by a mandrel transfer unit so that desired operations, for example printing, can be conducted at the respective stations.
The mandrel transfer units are controlled synchronously with the advance of the conveyor. The transfer units may be controlled by individual piston and cylinder units associated with each transfer unit or by a centrally controlled mechanism.
The aforementioned patent particularly describes an economic centrally controlled system for the transfer units. This mechanism generally involves the use of a cam which synchronously controls the operation of the mandrel transfer units with the advance of the conveyor. A single cam can be used for two or more of the work stations, and a cam follower operates with the single cam and is carried on an arm fixed for rotation with a central control shaft common to the respective stations.
An actuating lever controlling each of the mandrel transfer units is mounted for movement with this central control shaft. The lever for one of the control stations preferably comprises the arm carrying the cam follower. In this fashion, a single lever serves as the drive arm for the central control shaft and also as the actuating lever for one of the mandrel transfer units.